Today's Top Weather Stories
On Weather & Climate Through the Eyes of Mark Vogan
BREAKING NEWS
ACCUWEATHER.COM: Igor Rapidly Intensifies into Category 4 Hurricane
Mark's Ideas of Rapid Intensification of Igor holds true... See below for the details!
TRIPLE TROPICAL TROUBLE, BUT WILL THEY THREATEN THE US COAST?
By Mark Vogan
This dvorak image from NOAA shows that those "white colors" show the coldest cloud tops and just look at how round these are completely around the eye, these cloud tops btw are likely between -75 and -85C!
Hurricane Igor may "Rapidly Intensify", perhaps to a category 5 storm
Current Stats as of 11am ET
Category: 2
Max Sustained Winds: 105mph
Central Pressure: 970mb
Published: 7.30pm GMT
Going by how good Igor is appearing on various imagery presentations with a very impressive structure, looking very good for only a category 1 hurricane makes me wonder whether Igor as he enters a very healthy environment, may he grow steadily or will he undergo a phase of rapid intensification, say over a 12-hour period where he goes from cat 2 as he is presently to a 4 or 5 by say tomorrow morning remains a wonder to me at this time, I draw this conclusion by both looking at Earl and even Alex's reaction to certain atmospheric and oceanic conditions as well as their own individual structures and how well developed and organised they are, to be honest, like we have seen with a few of these systems this year already, they have been slow to get going, but once in a given area favorable for further growth, they appear to go "off to the races", Earl was closing in on cat 5 status with indeed max winds of 135mph and remember those flight level wind gusts recorded at 199mph, well I believe Igor is looking as healthy if not healthier than Earl and I believe as that shear drops to near nothing and waters are slightly warmer now than back east nearer the Cape Verde islands, then it's a possibility that Igor does rapidly intensify towards or to, category 5 intensity over the next day or so!
That of course is my own feelings and I may be wrong, whether this occurs or not doesn't matter at this point in time as he is no threat to the US for at least the next 10-days and at least 5-7 for any islands on the eastern edge of the Caribbean Sea so whether it becomes a superstorm or holds at a steady cat 3 strength is basically irrelivant to folks on the US mainland at this time but I wonder as time goes on and the models keep tracking Igor further and further west like they did with Earl, whether this time, the East Coast may not be so lucky...
Igor is HIGHLY LIKELY to grow further, whether it "bombs out" like I think it may given the current developments with it's improvement in appearance both within the inner core with it's very impressive eye and eye-wall structure, the CDO (Central Dense Overcast) and indeed the strong outflow around an increasingly "perfectly symmetrical" storm system. All these things you look for in an intensifying hurricane are in place, this will go to at least category 4, if not a 5 as this system looks better and stronger than even Earl was and it's only at cat 2 officially but I imagine the upgrade won't be long in coming here..
At this point in time, I hesitate to say as to where Igor is heading for. To be truthful, I do see a US hit but where? I can see this system perhaps tracking further south and west than one thinks and therefore may actually head towards the Gulf, not the East, but at the same time, if it takes the turn many think will happen, then the same areas that were threatened by Earl may be up for yet another worrying time ahead.
The good thing is that, East and Gulf Coast residents have time on their side, certainly where Igor is concerned, that's not to say another storm doesn't threaten the coast of the US BEFORE Igor may... but certainly Igor is well over a week away, and really anything can happen in such a long time frame.
I shall talk more on Igor tomorrow! Stay tuned!
TROPICAL DEPRESSION 12 NOW ON THE PITCH AND READY FOR ACTION!
Now that we have T.D 12 now born and official, it's looking as good as Igor did when he first appeared both over Africa and once out over the ocean, this system looks also very impressive, with strong convection over and around the center and this system is looking more and more circular and WILL become a named system, whether it's before or after the system over the eastern Caribbean Sea, YES THAT'S HOW BUSY THINGS HAVE BECOME!
The worrying thing about T.D 12 is that models have been persistent with not only this thing developing and heading west, like we're seeing with Igor, hundreds of miles to the west, but they're (like they've been doing with Igor) portraying the development into a powerful hurricane. It may well be far enough apart from Igor to intensify into a major hurricane and that would be something, to see two major hurricanes, both heading west over the central-tropical Atlantic with potentially the US awaiting BOTH of their wrath....
CARIBBEAN SYSTEM WILL DEVELOP
Of course, waiting the wrath of two potenially dangerous hurricanes out in the Atlantic is bad enough for sure, but we also have indeed the system over the eastern Caribbean which unfortunately also appears to have a future as a tropical cyclone, this very entity in fact may bring an impact to land and people well before either of the double trouble lurking in the Atlantic will and therefore it's not something to ignor or forget about. It's easy to be sidetracked or attention taken away by the bigger storm, but, like we saw with Hermine just last week in NE Mexico, Texas and up into the US heartland, these more local storm developments (for Central America or Mexico as well as the US) can be just as, if not more dangerous, simply because they pop-up, seemingly out of nowhere and can develop extremely fast, providing little time to prepare and can have greater impact than expected... as for the bigger storm thats takes weeks to cross the Atlantic, no matter how strong can be easier for preperation as well as monitoring it, it's storms like Igor or Earl, or indeed Frances, Isabel, Ivan that are watched constantly for days if not weeks therefore time is in the hands of those in harms way.
MORE ON THIS TOMORROW, STAY TUNED!
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Why is it tough for the Ocean and Atmosphere to Support Category 5 Hurricanes in the Atlantic?
Taking an In-Depth look at Maximum Potential Intensity
Projections in measuring the future power of a tropical cyclone is a science still in it's infancy but there are rules in which forecasters go by given the state of the playing field out there.
There are maps in which measure "MAXIMUM POTENTIAL INTENSITY" and certain years have sections of the Atlantic basin that see's higher MPI than other years, this year is higher given several factors which I will explain below. Other years the MPI is lower.. There are key areas of the Atlantic basin that "typically" has higher MPI than other areas.
THE STORM
In order for a storm to undergo either steady or rapid intensification, several factors must all come together at the same place at the same time, and that is extremely difficult to see happen, that's why in the Atlantic, it's rare to see a storm both rapidly intensify and or become a top-ranked category 5.
However, in order to see the Katrina's, Rita's, Wilma's, Ivan's, Isabel's, the actual maturity of the storm itself must then be looked at closely. 1) How well developed is the inner circulation i.e. the core.. the eye, the eyewall structure, the central dense overcast (CDO), is there a solid (thick), unborken ring of strong, self-generating thunderstorms (also known as hot towers) surrounding and making up the eye-wall?, is the overall circulation and air flowing uniformly around the system, is there good inflow at the surface and good outflow over top of the system where it releases excess energy out and away from the storm at the top, like an exhaust, remembering that a well formed, fully self driven hurricane, will recycle the kenetic energy it releases as outflow, as the air is forced overtop of the storm, then once outside the system's circulation, the high pressure that sits overtop of the storm will force the excess energy back to the ocean surface, where the storm will pick this back up, pulling it to it's core and then drawing up back up through the updraft columns where those strongest thunderstorms are racing around the center, regenerating air that was usable, then waste, and then transformed back usable energy, this re-cycling of air is repeated over and over again.
THE PERFECT SCENARIO THAT RARELY HAPPENS
High octane fuel that lies within a given area of ocean from surface to perhaps 250 to 300 feet down below the surface in which a warm current or even eddy flows (Gulf loop current or Gulf Stream), containing water temperatures above 85 degrees to depths of 250 feet or lower below the surface. A near perfect atmosphere above, say with no wind shear within a column spanning anywhere from 200 to 800 miles wide and upwards of 50,000 to 75,000 feet above the ocean surface. That same column which has a vertical thermal profile which supports temperatures at the surface and low-levels just above the ocean surface of 27-30C, plenty of heat and moisture which is vented off the very warm ocean into the low levels, compaired with an upper-level temperature of -70 to -85C, a vertical contrast which supports a very strong upward flow of air.. This would be considered a region supporting a high level of "Maximum Potential Intensity" if a storm was to move into this area.
LOOKING AT THE ATMOSPHERE
One must look at 1) SSP (Sea Surface Pressures), are they low enough for these systems to realistically drop their pressure further than it already is, 2) Is the overall atmosphere conducive for further intensification, i.e, the vertical profile of the atmosphere, is wind shear present, if so is it low enough to not hinder the storm's vertical structure of air flow? Is there a good vertical thermal profile in the columns of the atmosphere both containing the storm system and out ahead of it?, i.e temperature spread from the surface to the upper-levels, say from 27-30C at the surface to -70C or lower at the upper-levels..
So, if the pressures are uniformly low across a broad area of the tropical ocean, the air is plenty moist and warm, there is little to no wind shear across a broad area and indeed there is no dry air or other areas of low pressure nearby to inhibit potential intensification than there is no reason in which this type of atmosphere can't allow further growth of an already well organised and heatlhy storm system.
LOOKING AT THE OCEAN
When looking at the Atlantic Tropical Ocean Basin, there is a broad uniform area where water temperatures at the surface are 80F or 27C or warmer. Warm enough to support a tropical cyclone, but is it warmer enough to support intensification?
That uniform 80 degrees water at the "skin" of the ocean surface may only be at a depth of 50 feet, therefore, as a cyclone crosses over waters of 80 degrees which only supports that temperature of 80 down to 50 feet, then as the water is churned up, drawing deeper water upwards to the surface, then it may be just enough to support the cyclone's initial intensity or may even drop it's intensity as cooler waters below the 50 foot depth would perhaps lower the surface temperature from 80 to say 75 degrees....
This can be the case during the early season over the eastern Atlantic, nearer the African continent. That's why the so-called Cape Verde season, those long tracked storms that cross the entire-breadth of the tropical Atlantic only really kicks off in late August into September as waters aren't warm enough or deep enough, but once a near summer long heating of the ocean surface drives SST's to perhaps 83 degrees over the eastern basin, 85 over the central basin (where Igor is presently) and 86-88 degrees over the western basin do things really get going. Those cat 3s, 4s and 5s only form near the "peak of the season" when waters are closest to their peak...
What's important when looking at how strong a hurricane could potentially become can't be looked at by simply looking at what those SST's are, it could be over 85 degrees at the surface, but only for 50 feet down. If the "skin" temperature was the important factor and was say 85 degrees and covering much of the ocean surface in the tropics, then a much larger area of high percentage "maximum potential intensity" would then be given. However, it's temperature verses depth that counts as well as of course the state of the storm and it's atmosphere surrounding... yes, you didn't think it was as tough to get these kinds of ingredients infusing together did you?
Igor, is an example, and similar to both Isabel of 2003 and Ivan of 2004 where a storm literally "bombs out" over the open, central Atlantic. Waters are in the 85-87 degree range below and ahead of Igor and I believe they must stretch to depths lower than where the system would tap and churn colder waters, perhaps there's warm eddy's flowing and spinning under Igor, providing a constant feed of high octane fuel. The system is about as well organised and developed as it really can be, the atmosphere both within and surrounding the system is about as conductive as it could be also.. therefore the perfect scenario has and is unfolding, supporting Igor as a powerful category 4, 150mph hurricane.
What's more unusual about storms topping this intensity over the central Atlantic is that both Caribbean Sea and Gulf of Mexico supports warmer and deeper water than the Central Atlantic, however a net temperature of perhaps 1-2C warmer than normal may help spread that higher percentage of MPI furtherout into the tropical Atlantic, spreading a heat content more comparable to the Caribbean Sea eastwards and into the path of Earl and Igor of 2010, perhaps even in the form of an eddy which breaks off from the main channel within the Caribbean and Gulf.
Theoretically, you'll never find 100% maximum intensity, even with Katrina and Rita of 2005 topping 175mph sustained winds in the Central Gulf of Mexico (reasoning: perfect atmosphere, circulation maturity and extremely warm waters of 90 degrees, stretching perhaps 200 feet below the surface), even then it was probably around 70 to 80% MPI, given the ingredients in place.
Where Isabel topped cat 5 intensity over the western Atlantic, not too far west of Igor, the MPI was probably around 70 to 75% and I would say Igor is around 65 to 70% given the ingredients, perhaps nearing 70% if he can reach cat 5 status before an eye-wall replacement cycle commences.. also remember, it's tough for the atmosphere to support such power and these systems tend to peak quick and then they regenerate their own structure at the center where the eye becomes obsorbed by the surrounding circulation in which it basically swallows it up, often as this is occuring, you can often see a new eye already forming on the outer edge of the collapsing inner ring of the old eye...
So, the western Atlantic where waters are geberally warmer and deeper, have higher MPI percentages than over the central and eastern tropical basin. Some years the percentage in the central and eastern basin can be higher, like this year for example where waters are 1 to 2 degrees above normal, for the Caribbean and Gulf, they too can have a greater net energy potential than other years, in 2005 the potential was basically about as high as it could go in reality (around 70 to 80% MPI) as the uniform surface of the Gulf was 2-4 degrees above normal, plus the flow of the loop current was strong and right in the path of incoming hurricanes, the combo allowed Katrina and Rota to blow into top-ranked "scary" storms.. As for the western Caribbean Sea, that is basically the prime area of MPI in any given year but in 2005 Wilma was the perfect example as to just how warm and deep those waters are and how they react to a well developed storm.. Wilma probably topped 85 to 90% MPI given waters are warmest than anywhere else in the Atlantic basin(probably over 90 degrees and to depths over 450 to 500 feet below the surface).
What's Reaching Today's Blogs?
Fall Color Peaking in Alaska
Brett Anderson, Canada Expert, AccuWeather
How did this Summer Rank Globally?
Brett Anderson, Climate Change Blog, AccuWeather
Today's US Extremes
Courtesy of AccuWeather
High: 110 degrees at Death Valley, CA
Low: 23 degrees at Kremmling, CO
Today's UK Extremes
Courtesy of the Met Office
High: 72 degrees at Solent (Isle of Wight)
Low: 40 degrees at Aboyne (Aberdeenshire)
Today's Extremes here at my house
High: 64 degrees
Low: 55 degrees
TODAY'S COND
A generally pleasant day with sunny spells in between clouds, the haze was hazy but persistent, but there was a breeze which felt crisp. Without the wind and when there was more sun than clouds, it felt pleasant. The rain moved in by evening and combined with wind, made more a poor night.
Thanks for reading.
-Mark
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